1. Field of the Invention
This invention relates to liners used in refrigeration equipment, with particular reference to liners stressed in compression and methods of stressing the same prior to or during assembly to counteract tensile stresses and chemical penetration and attack which normally develop in liners during use and which reduces the effective useful life span of said liners.
2. Description of the Prior Art
In general the use of interior liners for decorative and utility purposes in refrigeration equipment is well known. Refrigeration equipment liners are normally made from, but are not limited to, thermoplastic materials and are normally designed to last 5 to 15 years. The conventional method of assembling liners into refrigeration equipment is to securely attach said liners at ambient room temperatures to the outer shell of the refrigeration equipment by screws, gluing, welding or other known means.
Heretofore, the methods used to assemble liners into refrigeration equipment have often resulted in the development of serve tensile stresses which cause premature failure of the liners during use. The liners contact when the temperature of the refrigeration equipment is reduced during operation, thus causing the tensile streses to develop. The tensile stresses are normally located near the means of attaching the liners to the outer shells of the refrigeration equipment. The localized tensile stress areas additionally provides a problem in that the surface foramine of the liners in the tensile stress areas tend to increase in size, thus allowing increased chemical penetration and attack of said liners. When subjected to tensile stresses, and particularly when accomplished by hostile chemical environments, liners may experience severe cracking and premature failure, thus reducing the effective life span of the refrigeration equipment.